Chrysler Repair: 1997 grand caravan 3.8 le: rough shifts, chrysler service manuals, diagnostic capability

Question
Roland I have had the tranny replaced twice now and have no doubt this is not the problem as it quickly returns. My van shifts hard at about 35 and 58 mph as if I ran over something in the road. It does it accelerating and decelerating. The abs light and check engine light go off and on intermittently. I had a wiring harness replaced for the abs and two trannys put in. any ideas?

Answer
Hi Sheryl,
My first suggeston would be to have the powertrain and transmission controllers' memories readout for fault codes. This can be done, often for free, at an Autozone parts store using a socket that is under the dash to attach a code reader. The codes should have 4 digits. Ask for the code numbers, what they mean, what they suggest doing, and the cost. If there is not such a store near you look for a special at an independent shop which should do the readout for under $40. This may not reveal the cause of your problems but it needs to be checked as to overlook the self-diagnostic capability of the vehicle is shortsighted.
Write back with the results and we can compare what you have been told to what the Chrysler service manuals say. Tell me a bit more about the history of the trans replacements. Is the most recent job still under warranty?
Why do you doubt it is a transmission problem (the shifting is controlled by a computer, so replacing the transmission is not necessarily going to eliminate all transmission problem causes)?
Roland
PS Please rate my answer, thanks.